Independent axis clamping apparatus and method

ABSTRACT

Apparatus for performing operations on a workpiece includes a clamping assembly mounted on a tool support for movement along at least one axis independent of the axes along which the tool moves. The clamping assembly includes clamping devices for applying clamping pressure to the workpiece, and a rotary drive mounted on the tool support for rotating the clamping devices around the independent axis. The clamping devices include clamping packs having a clamping roller mounted on a pneumatically driven slide for applying a programmed amount of clamping pressure to the workpiece.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Provisional U.S. PatentApplication No. 60/849,689 filed Oct. 5, 2006.

TECHNICAL FILED

This disclosure generally relates to manufacturing tools havingintegrated clamping fixtures, and deals more particularly with a toolhaving a workpiece clamp that can be moved along an axis independent ofthe direction of tool movement.

BACKGROUND

A variety of clamping devices are available for applying clamping forceto a workpiece in an area near a manufacturing tool operating on theworkpiece. The application of clamping forces near the manufacturingtool may reduce the need for complicated or cumbersome external clampingtools that may be needed in processes such as friction stir welding(FSW), to locate the parts being welded, prevent part separation duringwelding and react to process loads generated during the welding process.

One clamping device suitable for use with a FSW machine is disclosed inUS Patent Application Publication Number 2005/0092817 published May 5,2005, and assigned to The Boeing Company. In this prior patentapplication, the clamping device is mounted on a spindle head thatcarries the FSW tool. The clamping device is constrained to mechanicallyfollow the path of the FSW tool spindle. The spindle head is mounted ona machine tool arm that moves along any of 3 orthogonal axes in whichthe weld path, and thus the movement of the clamping device, isstraight. In some applications, however, complex curvatures ofworkpieces require more complicated movements of the FSW tool as well asthe clamping device. In these more complicated workpiece geometries, thetool path may vary with the changing slope and contours of theworkpiece. As a result, the clamping device may not always “track” withthe FSW tool to apply clamping force when and where it is required.

Accordingly, there is a need for a workpiece clamping apparatus that ismounted on a common support with a tool, but yet can be movedindependently of the tool so that clamping force can be applied at thedesired workpiece locations regardless of the orientation of the tool orthe support. It would also be desirable to provide a clamping apparatusand related method that coordinates the independent movement of theclamping device with movement of the tool. Embodiments of the disclosureare intended to satisfy these needs.

SUMMARY

Embodiments of the disclosure provide a clamping apparatus that may bemounted on a common support with a tool, such as a spindle housing, butwhich may be moved independently of the tool in order to closely followthe contour of a workpiece. The clamping apparatus may be mounted on aspindle housing for movement along at least one axis that is independentof the movement of the tool. The apparatus may include clamping rollersthat roll along the surface of the workpiece in order to reducefriction, and apply programmable amounts of clamping force to theworkpiece.

According to one disclosed embodiment, a manufacturing apparatus isprovided, comprising: a spindle support moveable along multiple axes; atool mounted on the spindle support for performing a manufacturingoperation on the workpiece; and, a clamping assembly mounted on thespindle support for movement along at least one axis independent of themovement of the spindle. The clamping assembly includes clamping devicesfor applying clamping pressure to the workpiece. The clamping assemblymay include a rotary drive mounted on the spindle support for rotatingthe clamping devices around the independent axis. The clamping devicesmay comprise clamping packs that include a clamping roller mounted on apneumatically driven slide for applying a programmable amount ofpressure to the workpiece. The rotary drive includes a stationaryportion secured to the spindle support, and a rotating portion driven bya motorized gear drive.

According to another disclosed embodiment, apparatus is provided forperforming operations on a workpiece, comprising: a tool assemblyincluding a tool moveable along multiple axes; and a clamping assemblymounted on the tool assembly, the clamping assembly including at leastone clamping device for applying clamping pressure to the workpiece, andmeans for mounting at least one clamping device for movement along atleast a first axis independent of the movement of the tool. The toolassembly may include a spindle support and the mounting means mayinclude a rotary mount for mounting at least one clamping device on thespindle support for rotation around the first axis. The mounting meansmay further include a slide assembly coupled with rotary mount formounting the clamping device for movement along a second axis, towardand away from the workpiece. The rotary mount may include a stationaryportion secured to the spindle, a rotatable portion, and a motorizeddrive for driving the second portion relative to the first portion. Themotorized drive may include an electric motor and a gear drive couplingthe motor with the rotatable portion of the rotary mount. The clampingdevice may include a roller clamp for engaging workpiece and means forbiasing the roller clamp against the workpiece. The biasing means maycomprise a fluid driven motor, such as a pneumatic cylinder. Theclamping device may include a clamping pack and a releasable connectionfor releasably securing the clamping pack on the mounting means, therebypermitting the use of interchangeable clamping elements.

According to a method embodiment, manufacturing operations are performedon a workpiece, comprising the steps of: contacting the workpiece with atool; moving the tool along any of multiple axes; moving a clamp alongat least a first axis independent of the movement of the tool; and,clamping the workpiece using the clamp. Contacting the workpiece withthe tool may comprise plunging a friction stir welding pin tool into theworkpiece while the workpiece is being clamped. The tool may be moved bymoving a spindle housing over the workpiece, and the clamp may be movedby rotating the clamp around the first axis as the spindle housing movesover the workpiece. The method may further comprise the step ofcoordinating the movement of the clamp with the movement of the tool.

Other features, benefits and advantages of the disclosed embodimentswill become apparent from the following description of embodiments, whenviewed in accordance with the attached drawings and appended claims.

BRIEF DESCRIPTION OF THE ILLUSTRATIONS

FIG. 1 is a functional block diagram illustrating a friction-stirwelding head assembly, including a clamping assembly according to anembodiment.

FIG. 1 a is an isometric illustration of a friction-stir welding headassembly.

FIG. 2 is an isometric illustration of a friction-stir welding spindlehousing and workpiece clamping apparatus according to one embodiment ofthe disclosure.

FIG. 3 is a sectional illustration taken along the line 3-3 in FIG. 2.

FIG. 4 is an enlarged illustration of the area designated as “FIG. 4” inFIG. 2.

FIG. 5 is an enlarged, sectional illustration of the area designated as“FIG. 5” in FIG. 3.

FIG. 6 is an exploded illustration of the FSW spindle and clampingapparatus shown in FIG. 2.

FIG. 7 is an enlarged illustration of the area designated as “FIG. 7” inFIG. 6.

FIG. 8 is a broad block diagram illustrating a system for performingmanufacturing operations on a workpiece.

FIG. 9 is a block diagram illustrating a method for performingoperations on a workpiece.

FIG. 10 is a flow diagram of aircraft production and servicemethodology.

FIG. 11 is a block diagram of an aircraft.

DETAILED DESCRIPTION

Referring first to FIGS. 1-7, a FSW head 10 (FIG. 1 a) includes a toolsupport comprising a spindle housing 12 pivotally mounted on a yolk 18by a pair of mounting arms 24 received in pivots 16 on the yolk 18. Themounting arms 24 form part of a saddle attachment 22 that may be securedto the spindle housing 12. Arms 24 mount the spindle housing 12 forrotation about the “A” axis.

The spindle housing 12 may contain a dual spindle drive 15 configured toseparately drive, advance and retract an FSW welding pin tool 46, and ashoulder tool 48 concentrically surrounding the tip of the welding pintool 46. Mounting of the spindle housing 12 on the pivot 16 enables theangle of the spindle housing 12, and thus that of the tools 46, 48 to beadjusted with respect to a workpiece 13 (FIG. 1 a). The spindle housing12 may also be mounted on a track 22 (FIG. 1 a), permitting the tools46, 48 to be advanced toward and away from the workpiece 13. It shouldbe noted here that while a FSW tool 46 and shoulder tool 48 have beenillustrated, various other tools may be employed for performingoperations on a workpiece 13 where clamping of the workpiece 13 may benecessary or desirable.

In order to clamp the workpiece 13 during an FSW welding operation, aclamping assembly generally indicated by the numeral 26 may be mountedon the spindle housing 12. The clamping assembly 26 broadly comprises astationary portion 28, a rotatable portion 30, and a pair of opposingroller clamp packs 44 disposed on opposite sides of the FSW tool 46. Thestationary portion 28 may surround the spindle housing 12 and includes apair of brackets 28 a respectively secured to the saddles 22. Therotatable portion 30 may include a generally cylindrical housing 30 amounted, as by bearings (not shown) on the stationary portion 28 forrotation about an axis 60 that may be independent of the axes ofmovement of the FSW tool 46, and shoulder tool 48. Housing 30 a may bealso connected to the stationary portion 28 by a rack and pinion gearassembly 34 which may be driven by a motor 32 mounted on the stationaryportion 28. The motor 32 may comprise, for example, without limitation,an AC electric stepper motor including an incorporated encoder (notshown) that generates signals representing the rotational position ofthe housing 30 a about the independent axis 60.

The lower portion of the housing 30 a may include a circumferentialconduit 40 which may house electrical lines and pneumatic control lines(not shown). A ring shaped, removable plate 38 may be mounted on thebottom of the housing 30 a, as for example and without limitation, byscrews to allow access to the conduit 40.

A pair of downwardly depending, spaced apart flanges 42 may be securedto the bottom of the plate 38, and provide a support for mounting theroller clamp packs 44. Ball lock pins 58 releasably attach the rollerclamp packs 44 on the flanges 42. The ball lock pins 58 provide a quickrelease means of mounting the roller clamp packs 44 so that they may beeasily removed and replaced with any of a variety of interchangeableclamping member configurations.

As best seen in FIG. 7, each of the roller clamp packs 44 may include agenerally rectangular housing 50 in which a slide member 52 is mountedfor confined sliding movement within housing 50 along an axis 62 that isinclined with respect to the central axis 60 of the FSW tool 46. Themovement of the slide member 52 along axis 62 may be independent of theaxes of movement (not shown) of the FSW tool 46 and shoulder tool 48. Abifurcated arm 54 may be secured to the bottom of the slide member 52. Aclamping roller 56 may be rotatably mounted on the bottom of each of thearms 54.

It should be noted here that although a pair of opposing roller clamppacks 44 have been illustrated, fewer or a greater number of the rollerclamp packs 44 may be employed, depending on the operation to beperformed on the workpiece 13. The housing 50 may include a pneumaticcylinder (not shown) which may be connected to drive the slide members52 using pressurized air delivered from a source (not shown) to theroller clamp packs 54 via pneumatic connections 14 (see FIGS. 4, 5 and7). The delivery of this pressurized air to the roller clamp packs 44causes slide members 52 to move downwardly, thereby extending the arm 54until the clamping roller 56 engages the workpiece 13 and applies acontrolled amount of clamping pressure to the workpiece 13.

Referring now also to FIG. 8, the operations performed on the workpiece13 by the FSW head 10, including workpiece clamping, may be operated bya controller 70 which may comprise, without limitation, a programmedcomputer or PLC (programmable logic controller). Controller 70 maycontrol a machine tool 72 that moves the FSW head 10. Controller 70 mayalso control the operation of the FSW tools 46, 48 which performs theFSW welding operation on the workpiece 13.

The controller 70 may further control a source of pressurized air, (notshown) as well as pneumatic logic (not shown). The pneumatic logiccontrols the roller clamp packs 48, by controlling the pressure of theair supplied to the cylinders in the roller clamp packs 44. Thecontrolled air pressure regulates the amount of clamping pressureapplied to the workpiece 13 by the clamping rollers 56. The controller70 may send control signals to the motor 32, which may in turn controlthe rotational position of housing 30 a, and thus the rotationalposition of the clamping rollers 56 on the workpiece 13. Controller 70may coordinate the movement of the machine tool 72, the operation of theFSW tool 46 and shoulder tool 48, the rotational position of theclamping rollers 56 and the pressure applied to the workpiece 13 by theroller clamp packs 44.

Attention is now also directed to FIG. 9 which illustrates the basicsteps of a method for performing manufacturing operations on a workpiece13. Beginning at step 74, controller 70 issues control signals thatresult in movement of the spindle housing 12 into proximity to a targetlocation on a workplace 13. Next, at step 76, the controller 70 controlsmotor 32 to rotate the roller clamp packs 44 into position, followingwhich the roller clamp packs 44 are actuated at 78, causing clampingrollers 56 to apply clamping force to the workpiece 13

With the workpiece 13 having been clamped, the FSW tool 46 is plungedinto the workpiece 13 as shown at step 80. The FSW head 10 moves thetool 46 over the workpiece 13 as shown at step 82. As the tool 46 isbeing moved through a pre-programmed path, the controller 70 coordinatesmovement of the roller clamp packs 44 around the independent axis 60with movement of the tool 46, as shown at step 84. In order tocoordinate these movements, motor 32 is controlled to rotate therotatable portion 30 of the clamping assembly 26, so that the clampingrollers 56 properly track movement of tool 46 and the contours of theworkpiece 13. If required, the air pressure applied to the roller clamppacks 44 is adjusted at step 88 so that the desired level of clampingforce is maintained regardless of the position of the tool 46 on theworkpiece 13. When the FSW operation is ended at step 90, the rollerclamp packs 44 may be deactuated at step 92, thereby unclamping theworkpiece 13.

Referring now to FIGS. 10 and 11, embodiments of the disclosure may beused in the context of an aircraft manufacturing and service method 94as shown in FIG. 10 and an aircraft 96 as shown in FIG. 11. Duringpre-production, exemplary method 94 may include specification and design98 of the aircraft 96 and material procurement 100. During production,component and subassembly manufacturing 102 and system integration 104of the aircraft 96 takes place. Thereafter, the aircraft 96 may gothrough certification and delivery 106 in order to be placed in service108. While in service by a customer, the aircraft 96 is scheduled forroutine maintenance and service 110 (which may also includemodification, reconfiguration, refurbishment, and so on).

Each of the processes of method 94 may be performed or carried out by asystem integrator, a third party, and/or an operator (e.g., a customer).For the purposes of this description, a system integrator may includewithout limitation any number of aircraft manufacturers and major-systemsubcontractors; a third party may include without limitation any numberof venders, subcontractors, and suppliers; and an operator may be anairline, leasing company, military entity, service organization, and soon.

As shown in FIG. 11, the aircraft 96 produced by exemplary method 94 mayinclude an airframe 112 with a plurality of systems 114 and an interior116. Examples of high-level systems 114 include one or more of apropulsion system 124, an electrical system 118, a hydraulic system 120,and an environmental system 122. Any number of other systems may beincluded. Although an aerospace example is shown, the principles of theinvention may be applied to other industries, such as the automotiveindustry.

Apparatus and methods embodied herein may be employed during any one ormore of the stages of the production and service method 94. For example,components or subassemblies corresponding to production process 102 maybe fabricated or manufactured in a manner similar to components orsubassemblies produced while the aircraft 96 is in service. Also, one ormore apparatus embodiments, method embodiments, or a combination thereofmay be utilized during the production stages 102 and 104, for example,by substantially expediting assembly of or reducing the cost of anaircraft 96. Similarly, one or more of apparatus embodiments, methodembodiments, or a combination thereof may be utilized while the aircraft96 is in service, for example and without limitation, to maintenance andservice 110.

Although the embodiments of this disclosure have been described withrespect to certain exemplary embodiments, it is to be understood thatthe specific embodiments are for purposes of illustration and notlimitation, as other variations will occur to those of skill in the art.

1. Manufacturing apparatus, comprising: a tool support movable alongmultiple axes, said tool support having at least opposing sides; a toolmounted on the tool support for performing a manufacturing operation ona workpiece; and, a clamping assembly mounted on said at least opposingsides, said clamping assembly having an end, said clamping assemblymoveable along at least a first axis independent of the movement of thetool, the clamping assembly including at least one clamping devicemounted at said end of said clamp assembly and extendable from said endof the clamping assembly for applying clamping pressure to theworkpiece; said at least one clamping device further comprises a rollerclamp for engaging the workpiece and means for biasing the roller clampagainst the workpiece.
 2. The manufacturing apparatus of claim 1,wherein the clamping assembly includes a rotary drive on the toolsupport for rotating the at least one clamping device around the firstaxis.
 3. The manufacturing apparatus of claim 2, wherein the rotarydrive includes: a rotary mount including a first portion fixed to thetool support and a second portion rotatably coupled with the firstportion, and a motor for rotating the second portion relative to thefirst portion.
 4. The manufacturing apparatus of claim 1, wherein thebiasing means includes a fluid driven motor.
 5. The manufacturingapparatus of claim 1, wherein: the at least one clamping device includesa slide, and the roller clamp is mounted on the slide for slidingmovement along a second axis toward and away from the workpiece.
 6. Themanufacturing apparatus of claim 1, wherein: the clamping assemblyincludes a mounting on the tool support, and the at least one clampingdevice includes a clamping pack and means for releasably coupling theclamping pack to the mounting.
 7. The manufacturing apparatus of claim6, wherein the clamping pack includes: a slide assembly, and a frictionreducing clamping member mounted on the slide assembly for engaging theworkpiece.
 8. The manufacturing apparatus of claim 6, wherein theclamping pack includes: a slide assembly, and a friction reducingclamping member mounted on the slide assembly for engaging theworkpiece.
 9. The manufacturing apparatus of claim 1, wherein: the atleast one clamping device includes a slide, and the roller clamp ismounted on the slide for sliding movement along a second axis toward andaway from the workpiece.
 10. The manufacturing apparatus of claim 1,wherein: the clamping assembly includes a mounting on the tool support,and the at least one clamping device includes a clamping pack and meansfor releasably coupling the clamping pack to the mounting.
 11. Apparatusfor performing operations on a workpiece, comprising: a tool assemblyincluding a tool movable along multiple axes; and, a clamping assemblymounted on, the clamping assembly including at least one clamping devicefor applying clamping pressure to the workpiece, and means for mountingthe at least one clamping device for movement along at least a firstaxis independent of the movement of the tool; the at least one clampingdevice having: a roller clamp for engaging the workpiece, and means forbiasing the roller clamp against the workpiece.
 12. The apparatus ofclaim 11, wherein: the tool assembly includes a spindle housing, and themounting means includes a rotary mount for mounting the at least oneclamping device on the spindle housing for rotation around the firstaxis.
 13. The apparatus of claim 12, wherein the mounting means includesa slide assembly coupled with the rotary mount and mounting the clampingdevice for movement along a second axis.
 14. The apparatus of claim 12,wherein the rotary mount includes: a stationary portion secured to thespindle housing, a rotatable portion coupled between the stationaryportion an the clamping device, and a motorized drive for driving thesecond portion to rotate relative to the first portion.
 15. Theapparatus of claim 14, wherein the motorized drive includes: an electricmotor, and a gear drive coupling the motor with the rotatable portion.16. The manufacturing apparatus of claim 11, wherein the biasing meansincludes a pneumatic motor.
 17. The manufacturing apparatus of claim 11,wherein: the mounting means includes a slide, and the roller clamp ismounted on the slide for sliding movement along a second axis toward andaway from the workpiece.
 18. The manufacturing apparatus of claim 11,wherein the at least one clamping device includes: a clamping pack, anda releasable connection for releasably securing the clamping pack on themounting means.
 19. The manufacturing apparatus of claim 18, wherein:the mounting means includes a slide assembly, and the clamping packincludes a friction reducing clamping member mounted on the slideassembly for engaging the workpiece.
 20. Manufacturing apparatus,comprising: a tool support movable along multiple axes; a tool mountedon the tool support for performing a manufacturing operation on aworkpiece; and, a clamping assembly mounted on the tool support formovement along at least a first axis independent of the movement of thetool, the clamping assembly including at least one clamping device forapplying clamping pressure to the workpiece; the at least one clampingdevice having: a roller clamp for engaging the workpiece, and means forbiasing the roller clamp against the workpiece.
 21. The manufacturingapparatus of claim 20, wherein the clamping assembly includes a rotarydrive on the tool support for rotating the at least one clamping devicearound the first axis.
 22. The manufacturing apparatus of claim 20,wherein the tool comprises a friction stir welding (FSW) tool.